System.FormatException when MessageAttributes contains type number

[codrinandronic]

Describe the bug
When an SQS message contains MessageAttributes with Type Number, an exception of type System.FormatException is thrown when the message is picked up from the queue.

Steps To reproduce
Send an SQS message coining the following MessageAttributes:
"MessageAttributes" : {
"TotalValue" : {"Type":"Number","Value":"100"}
}

Expected behaviour
Message should be picked up with no exception.

Actual behaviour
The following exception is thrown:
System.FormatException: The input is not a valid Base-64 string as it contains a non-base 64 character, more than two padding characters, or an illegal character among the padding characters.
at JustSaying.Messaging.MessageSerialization.NewtonsoftSerializer.GetMessageAttributes(String message) in //src/JustSaying/Messaging/MessageSerialization/NewtonsoftSerializer.cs:line 54
at JustSaying.Messaging.MessageSerialization.MessageSerializationRegister.DeserializeMessage(String body) in //src/JustSaying/Messaging/MessageSerialization/MessageSerializationRegister.cs:line 45
at JustSaying.AwsTools.MessageHandling.Dispatch.MessageDispatcher.DeserializeMessage(IQueueMessageContext messageContext, CancellationToken cancellationToken) in /_/src/JustSaying/AwsTools/MessageHandling/Dispatch/MessageDispatcher.cs:line 79

System information:

• OS: Windows 11
• Library Version 7.0.0 and above
• .NET version 8

Additional context
Both SystemTextJsonSerializer and NewtonsoftSerializer implementation of GetMessageAttributes() handle only String data types. Everything else is considered Binary. But AWS documentation specifies that Message Attributes can have 4 data types: string, number, binary and custom which should be handled.

[martincostello]

From MessageAttributeValue.DataType:

Amazon SQS supports the following logical data types: String, Number,
and Binary. For the Number data type, you must use StringValue.

We need to add support for Number in at least these two places:

JustSaying/src/JustSaying/Messaging/MessageSerialization/NewtonsoftSerializer.cs

Lines 64 to 78 in 56b8877

	var propData = prop.Value;
	if (propData == null) continue;
	var dataType = propData["Type"].ToString();
	var dataValue = propData["Value"].ToString();
	var isString = dataType == "String";
	var mav = new MessageAttributeValue
	{
	DataType = dataType,
	StringValue = isString ? dataValue : null,
	BinaryValue = !isString ? Convert.FromBase64String(dataValue) : null
	};
	dict.Add(prop.Name, mav);

JustSaying/src/JustSaying/Messaging/MessageSerialization/SystemTextJsonSerializer.cs

Lines 71 to 81 in 56b8877

	var dataType = obj.Value.GetProperty("Type").GetString();
	var dataValue = obj.Value.GetProperty("Value").GetString();
	var isString = dataType == "String";
	attributes.Add(obj.Name, new MessageAttributeValue()
	{
	DataType = dataType,
	StringValue = isString ? dataValue : null,
	BinaryValue = !isString ? Convert.FromBase64String(dataValue) : null
	});